Biomechanical Evaluation of a Novel Six Strands, Non-locking Flexor Tendon Repair Technique

Background: We designed a new non-locking six-strand suture technique (Li-Wee) as an evolution of our previous work. The aim of this study is to biomechanically compare repairs using this technique with FiberWire^® 4-0 versus Prolene^® 4-0. Methods: Thirty porcine flexor tendons were harvested for the experiments. A transverse cut was made in the middle of the tendons to allow for tendon repair. Repairs were made equally by using the Li-Wee technique with FiberWire^® 4-0 and Prolene^® 4-0. The ultimate tensile strength (UTS), load to 2 mm gap force, stiffness and repair times were measured under static testing. Furthermore, cyclic testing was performed on five specimens with the circumferential epitendinous suture from each repair group to evaluate their gap formation under cyclic loadings and final UTS. Results: The mean UTS of repairs using FiberWire^® was 81.3 ± 10.3 N while repairs done with Prolene^® was 66.7 ± 8.3 N under static testing, and 98.7 ± 4.9 N for repairs using FiberWire^® and 68.3 ± 10.4 N for repairs using Prolene^® under cyclic testing. Comparing FiberWire^® and Prolene^® repairs, the load to 2 mm gap force was 37.6 ± 8.4 N and 31.0 ± 10.9 N; stiffness was 6.5 ± 0.9 N/m and 8.1 ± 1.0 N/m; repair times were 466 ± 45 s and 465 ± 62 s, respectively. A statistically significant difference was found between groups for UTS under both static and cyclic testing, as well as stiffness. Conclusions: This study has shown that six-strand non-locking Li-Wee flexor tendon repair using FiberWire^® offers satisfactory repair strength, adequate stiffness and 2 mm gap force.